Do They Each Have Their Own Man in Them?

Letter-Equations
Letter Equations are well known phrases or facts where the key words have been replaced with the first letter of that word. These are often in the form of an equation, which contain a number, an = sign and the rest of the obscured phrase or fact.

63 = M of J

Hint

It makes earth's single M seem pathetic...

Answer

63 = Moons of Jupiter

The total number of moons now stands at 63, but many tiny moons may exist that have yet to be discovered.